Automatic telephone system



J. E. OSTLINE 2,639,331

May 19, 1953 Y AUTOMATIC TELEPHONE SYSTEM Filed March 11-, 1947 BIOI 9 Sheets-Sheet 1 SM|OOA SMIOOB SMIOOC 4 MARKER SW.

I20 j 0 i i? o If H waa o O INV NTOR.

John E. 'Ostline J. E. OSTLINE AUTOMATIC TELEPHONE SYSTEM May 19 1953 9 Sheets-Sheet --2 Filed March 11, 1947 INVHVTOR. John E. Osfline Afiorneys BY 09mm,

May 19, 1953 J. E. OSTLINE 2,639,331

AUTOMATIC TELEPHONE SYSTEM Filed March 11, 1947 9 Sheets-Sheet 3 cm O Q E. i

LL. 2 IO INVENTOR. John E. Osrline Attorneys mmww w mw M J J; E. os'TuNE' W 2,639,331

AUTOMATIC TELEPHONE SYSTEM 9 Sheets- Sheet 4 mkwh. I

WL E

May 19, 1953 Filed March 11. 1947- oow mwazE Rm n 62: W L v 2% N8 .3 8 o 58 -88 Inventor By John E. Osfline MJW M14 m Aflorne s 55% I Si 9 Shee'is-Sheet 9 Inventor John E. Osfline I Attorneys NET J. E. OSTLINE AUTOMATIC TELEPHONE SYSTEM May 19, 1953 Filed March 11, 1947 Patented May 19, 1953 v PATENT oss- I CiE-l .aosassi AU'IZQMQTIGI TELEPHQNE. o

' John E. O'stIinc, Chicago Ill-,1 asslgnor to Aut matic Electric Laboratorie Ina, Ghicago, 11.1. a corporation of Delaware AnplicationMcrclr 1'1, 1947 Serial-No: 'tfifiil Z1; Claims.

The present invention relates to automatic elephone sys ems" and. more parti ularly o improved automa ic: switching apparatus for setine m telcplione connections.

It is an object oi the present invention to poo vide a telephone system in which! connections may he set up y automatic switching? apparatus to telephone lines employing directory numbers corresponding tothe lineterminals, wherein each individual: automatic" switch utilized comprises; re ister mechanism that does not require releas mg and resetting. between successive signals: re cerved: thereby in order to control successive coordinate operations of the switch.

Another object of the invention is: to provide an automatic: switch that comprises improved: register mechanism which cooperated in accordance with a first signal received directly from its home position to a first position in or? due tobring about a first operation of the switch corresponding to the first. signal received, and then operated in accordance with a second sis. nal inclined directly from its first position to a second position in order to: bringabouta sec-r nd: operation of the switch corresponding to the second signal received.

Another'object or the invention is to provide in an automatic telephone system a finder incorporating an automatic switch of the character described! Another object of the invention is to provide in an. automatic telephone-system a selector inv corpora-tine an automatic switch of the char-e actor described.

Another object of the inven ion i to pr vide in n au omatic telephone ystem a connectcn' incorporating: an automatic switch of the char actor described.

A further object of the invention is to provide an au omatic swi ch ct improved cons ruction and arrangement that comprise a plurality o members and aplurality of contact sets and a plurality of selecting magnets respectively associated with the members and with the contact ets, whereby each. selecting ma net is opera ive simultane usly to select the corresponding memher and to operate the corresponding con act set.

A further object of. the invention is to provide in an automatic switch oi the cocrdinatetype. impr ved clutchwontrol mechanism common to the bars and to the contac sets, whereby, when any bar is clutched to the asso iated operating element, the corresponding contact set 'isoperated. 7

' tus; Fig. t is an enlarged iragmcntary secti nal Further features 01' the invention pertain to the. particular musement oi. he circuit els-' ments of the system. w ere y the atove cutr lined and additional operating: t am-res t crcot.

ustrating thestructural. details or this portion; of the swit hing apnara us and particul rly the details oi he first switch mechanism incorporw ted therein; Fig, 3 is an enlarged fragmentaryv side elevational view of the upper. left-hand por tion of the fir t swi ch. mechanism shown in Fig.

together with the associated p rtion of the.

sup orting structure for the switchin annexe view, taken along the line 4-4 in Fla 2;. oi. the switching apparatus, illustrating additional structural details of. the upper portion of the first switch mechanism hown in Figs 2. and a; Fig. 5 is an enlarged fragmentary sectional view. taken along the line 5 5v in Fig. 2, oi the switch= ins acperatus. llustrating additional structural details of the upper portion of the first switch mechanism shown in Figs. 2 3 and a; and Figs.

6. 0 11, inclusive. taken t gether illustrate the details of a complete automatic telephone sys tem and incorporated therein switching apparatus of the character oi that shown in Figs. 1 to 5, inclusive. More particularly, Figs. 6, '7, 8 and 9 should be arranged from left to right in cnd tos end relation; and, Figs. 10 and 1.1 should be ar ranged, fr m left to right in end-'to-end relation and disposed, resp ct vely, below Figs. 6 and 7 in order to form a unified dia r m- ReIerring now, more particularly. to Figs 6 to 11, inclusive, of the drawings, there is lus rates an automatic telephone syst m c mprising an exchange terminating 1,000 subscriber lines, in eludin the subscriber lines 580 and, 635. respec vcly extending to subscriber substations TQM.

and 17802, Each subscriber line is providsdwith a line circuit individual thereto; the line sin to the subscriber lines 690 and 695, as shown in Fig. 6. Also, the system comprises switching apparatus, including ten groups of finder-selector links; the second group including the first finder-selector link illustrated, which comprises the finder 600, shown in Fig. 6, and the selector 100, shown in Fig. '7. Also, the switching apparatus comprises ten groups of connectors each including ten individual connectors; the ninth individual connector 800 in the second group being shown in Figs. 8 and 9. Moreover, the system comprises a control circuit and an allotter individual to each group of finder-selector links; the control circuit I000 and the allotter H00, respectively shown in Figs. 10 and 11, being individually associated with the second group of finder-selector links, including the first link illustrated. Each group of finder-selector links serves a corresponding group of 100 of the subscriber lines; and each group of connectors serves a corresponding group oflOO of the subscriber lines. Specifically, the second. group of finderselector links, including the first link illustrated, serves the second 100 line group of subscriber lines; and the second group of connectors, including the ninth connector 800 illustrated, serves the second group of 100 subscriber lines.

Preferably, the line circuits are identical; the line circuits 650 and 610 respectively comprising, as shown in Fig. 6, line relays R655 and R615, and cut-off relays R660 and R600; and are connected and arranged in a manner more fully explained hereinafter.

Preferably, each of the links is identicalto that illustrated, comprising the finder 600 and the selector 100. The finder 600, shown in Fig. 6. comprises a switch mechanism SM600; and a relay group including a start relay R630, a test relay R640 and a connect relay R625; as well as a selecting device or marker switch 620 of the forward-stepping rotary type; and is connected and arranged in a manner more fully explained hereinafter. The switch mechanism SM600 is identical to that shown in Figs. 1 to 5, inclusive, and described hereinafter; and comprising, among other elements, ten marking magnets MM60I to MM600, inclusive; ten primary members or bars P360! to P3600, inclusive; a primary magnet PMGI I; one hundred primary contact sets P06ll to P0600, inclusive; and ten sec ondary contact sets S060! to S0600, inclusive.

More particularly, in the switch mechanism SM600 the ten secondary contact sets $06M to S0600, inclusive,,are respectivelyassociated with the ten marking magnets MM60I to MM600, inclusive; whereas the one hundred primary contact sets PCGl l to P0600, inclusive, are associated with the ten primary bars PB60I to P3600, in-

clusive, in the manner indicated below.

Disposition of the Primary Contact Primary Sets (Left to Right) Finally, the switch mechanism SM600 comprises ten riser busses RB60I to RB600, inclusive, respectively terminating in the ten secondary contact sets $06M to S0600, inclusive. Further,

"- explained hereinafter.

each of the ten riser busses RBSOI to R3600, inclusive, terminates in ten of the primary contact sets respectively disposed in the ten groups of primary contact sets. For examples, the riser bus R1360! terminates in the ten primary contact sets P061 l, P0620, etc., and P0602; the riser bus RB602 terminates in the ten primary contact sets P06l2, P062l, etc., and P0603; and the riser bus R3600 terminates in the ten primary contact sets P0610, P0629, etc., and P060l.

In the finder 600, the marker switch 620 is of the forward-stepping rotary type, as previous- "ly noted, and comprises a double-ended wiper 62l provided with an associated contact bank,

including ten individual contacts; and a magnet M623 for driving the wiper noted step by step in the clockwise direction. Also, associated with the marker switch 620 is a set of switch springs S626, which is actuated when the wiper noted is driven away from its home position, wherein it engages the tenth contact in the associated contact bank.-

The selector 100, shown in Fig. '7, comprises a switch mechanism SM; and a relay group including a test relay R140, a line relay R150,

a hold relay R160, a digit relay R110, a control relay R180; and a connect relay R125; as well as a' selecting device or marker switch of the forward-stepping rotary type; and is' connected and arranged in a manner more fully The switch mechanism SM10'0 is substantially identical to that shown in Figs. 1 to 5, inclusive, and described hereinafter; and comprises, among other elements, tenmarking magnets MM10I to MM100, inclusive; ten primary members or bars P310! to PB700,

Disposition of the Primary Contact Pnmay Sets (Left to Right) P0757, P0758, etc., and P0756, P0766, P0767, etc., and P0765. P0775, P0776, etc., and r0774. P0784, P0785, etc., and P0783. P0793, P0794, etc., and P0792. P0702, P0703, etc., and P0701;

Finally, the switch mechanism SM100 com-" prises ten riser busses R310] to RB100, i nclusive, respectivelyterminating in the ten secondary contact sets S0101 to S0100, inclusive. Further, each of' the ten riser busses RB10I to RB100, inclusive, terminates in ten of the primary contact sets respectively disposed in the, ten groups of primary contact sets. For examples, the riser bus R1310! terminates in the ten primary contact sets'PCH l', P0120, etc., and P0102; the riserbus RB102 terminates in the ten primary contact sets P01I2, P012 l, etc., and P0103; and the riser bus R3100 terminates inthe ten pimary sets P01l0,'P0129, etc., and

assesses the ilmier its. the marker switeh its is oi the ie'iW' eppihs r tei'y type. a previeiisly tasted, semprises e e euble=enciei wiper "1;! Provided with sseeisteei can-test bank nelu ing teii i di i al contests; and e meshet M723 for driving the wiser net si st p y step n the eioels ise direction. lse, a socia ed with the marker sw tc 1.20 is s set i sw t h springs S742 which is actuated hen th W per liste is cliiven ewsy i erh-its h me pesi i ii wh rein it engages tenth ceht e he ass iated eiiteet hens:

Ereie sbly eee oi th eonheete s id nt cal o the eehi eetor 8.00, sho n in Fi s: 3 an 9, tha comprises e switch meeh nisz SMttlil; and a relay group ineliiding an answer $51843 Ba e a. line .reley a held relay 33 a rensiei relay R849 e ring est-oi? rel y B85 a usy reiey Base, at test relay B88 two eent el relays 38 6 end, 3830' and i conn c relay R92 as Well a selee ine de ee 17 marke swit h 32% of the iQrwarcl-stepplhg ietery type; and s estinee ed and er tinged iii a mann r more ii y ex.- p'lsineci hereihei er, he swit meehenism Sit 9 .10 sub n ially identical t9 t at sho n in Figs. 1 to 5, inclusive, and described hereinafter; nd ompri es, emehg o her element en markhis magnets MMSB te Mildew, inclus ve; en primary members or bars P13 9! to P3969; in-

lusi e a primary magnet EMSH on undred primary eentaet sets POW to PCS in usi d en sees iciei'y ent-se sets $09M o 6 00. cl s ve- Mere p rticularly, in th itch mechanism SMSBG, the ten secondary eenteet sets see to 39 iiielu i e; a e esp ctively associated with the en insistin magnets MM fli ts Nil 1 W, inclusive; Whereas the one hundred primary cone tact sets PCS to P6900,'inclusive, are associated with the ten min stry bays PBQBI to P193906, inclusive, in the manner indicated. below:

D sp i onef the l riii iy o tes Primary Ems em (Left to Right) PC-910, T6911, etc., and PG919. I P6929, P0920, em, and 10928. P9938, P0939, 6128., apd.PC9 37.

P6947, Peels, ete, nd P0946, P0956, P0957; etc, and F6955.

P 5, Ewe i, and i=0 T0974, PG-975, etc., and EC P5983, 1 693.4, 13110;, and P9982. P 9 0 93, 11G, sa 36 91! PGJULPGQUQ, um, and PGQQO.

Finally, he switeh mee sh sm SMtfifl eem prises ten husses, REM! to Rhett, nclusive, re p e i ly erminating the ten se ondary content s s SQBOI to $0880 nehisi e- Fui'thei',

eeh oi th ten riser mis es BB9! t9 31.35%.

i elusive, t rminates in the n p mary e hte t ispeeti ely dispos d in th two grougs' oi pr mer? es tsct sets. For example he riser us .RBfiili t rmi at ihthe en p imary "contact ets P69), RS928, ete, n PC551 th risei' bus R3302 t rminates in the ten primary 0011- test sets PCSU, 6929, e, PC9112; and e r ses bus B139 0 terminates in the te primary eoiiteet. sets P6919, 63 8. ete, end PC990- In he s mes 8% the ma ker switch 92 is i h forward-steppin i' tei type, s preieu y n t-ed, end. s mpi'ises s dilllbl filli id W p r fit! piievitlesi with a sociated ehteet ehls ih l 'elihg t ii i si ithis cohtsets; the e mesh t .MQZB .for el ins Wihe iis eti step by st p in h eleeliwise liie ticm- Also esss= ciated with the marker switch' 920, is a set of est-elit xtending str cturesetuetee th he e mesh cehtec't in shrines $325 which wipe? het'tlis ii ties. wherein it emsese the tent the essoeie eo ontest bank,

The control circuit IMO is commonly assoelated with the iihdei-=seleete links n the se one gre n emi eeiiiprises e relay roup including a start r y R1010 at stop relay R1920. a step rel yi tl 039, two t eiisier releys E10 0 a d R1050, a reset relay B ew, fi e ounti g r l B1065. B1019, B101 B4880 E1085, nd a reflex relay E 999; and, is eeii eted and arr nged i e manner more ll ex ained here na terlhe silotter HDD s eenim hly esseeieted with the ihsisi' seleetei' links the seco d g oup and eihg i'ises s .reley group ihel idihg e plurality 9 ittle r lays 'respeetiv ly eerrespo dihg to the finder leeter l he in this gr up; the li k reley Billie he individual t the rst iin er-seleetor ittle illustrate-ii in this group, end the little relays EH 0 ens R! I!!! bei g r spectively i d dual Le nte m diate unit, not shown in this g een v 11 th no shown, in'this 39 59;

s t i'e sy it! I 5; a links- .,-is enneetr ey R! 60; a cut-through relay R 0: at start reley R! H5; a link start relay EH8 2 een rol elay EH; and two tim r relay R! 189 and .R! le all eonneetesi ha arran ed i a mennei mor fully es ribes heie eiter- Structure and operation of the switching apparatus As P JQ'ViQ lSIY mete eseh of the finders e0 tei, th sele tsrs etet, end the so tee s 5 7i etet, esiiiprises e s iteh m eh hi substen ielly itle tiesl to at n Figs. 1 to 5, helu i e- Re erring n w m r part cularly, t Figs 1 ts inelusive, the s ching a ar tus there i tes ed eeihprises at suppo ing ram we s a p urali y s spaced-ap rt. ptsnains ese e members 20! and e urality f horizonta y ext ndin a gle members 3 2. rig dly s s-reel. tee ther te term an upstanding, h rilse the. sup n frame .200 iiieliicl s e horizontally xtend n t ev rail 203. and at h riz ntally x e d g b ttom rail, set sho n seeur ci to he angle members 0.!- Fiisther. the supporting frame Z D-ee r a horizontally extenqig g bare=wire bank 2H] inluding lQO e iicle ter s ts; each in siuel eondeeter et ome n at least, thr i dividua eneluetors inehiclmg a pos tive n cond r, a negati line eomi eter nd, a r l, conc sill lln' f th ohdiietor s t being elie d a The op-ee e en s of the arewine h uls 2 3, W l as speeecl pert .iizi tl e e pei'tiens t. ms su this s ep by upsta ding l a c am-net "-isinsulates lamps diseased at leftfi anpl end ef the hareire log-n1; 2131 eing indiestecl at 242- The ii' siiletiiis amp H2 eempiises two up anding strips of n ulate ns material 213 and 2M between hieh the indiieuel eonciuctors in the con uct r se s 21! e eu are eteinetl in mess in sp-eeezi esert i'elsti i. as well as ups iislins e isnnel 1. secured to he shale member 25!! iii sitter .te reteiiii he 1.1 siilet ng s ips m exist 2'4 s lamp delstien- Alse the pertie ler ii -sslstiiig clamp 2 t d spos at the let e head xist e the re-w re e k i s pi'eviele Wti'h strip of i. misting mat rie 215 thi'eiigh whieh the individual QllQ QtQ in the C il llfii l sets 2H, ete-z pmie he e y the insulating strip '2l8 constitutes a terminal aceaes strip. The ends of the individual conductors in the conductor sets 2l I, etc., project slightly beyond and to the left of the terminal strip 2I5 and provide terminals, whereby the individual conductor sets may terminate 100 subscriber lines.

The supporting frame 200 carries a plurality of vertically extending and horizontally spacedapart switch mechanisms, SMIOA, SMIO0B, SMIOUC, etc., on the front side thereof, as well as a plurality of vertically extending and horizontally spaced-apart switch mechanisms SMIO0X, SMIO0Y, etc., on the rear side thereof, as best illustrated in Fig. 4. The individual switch mechanisms SMIO0A, SMIO0B, etc., disposed on the front of the supporting frame 200 and the individual switch mechanisms SMIO0X, SMIO0Y, etc., disposed on the rear of the supporting frame 200 are arranged in staggered relation; whereby a switch mechanism on the front of the supporting frame 200 and a switch mechanism on the rear of the supporting frame 200 have common access to the opposite sides of an intermediate section of the bare-wire bank 2I0. Each individual switch mechanism SMIO0A, etc., is provided with an upstanding and outwardly projecting supporting base, which is secured to the top rail 203 and to the bottom rail, not shown, of the supporting frame 200 by an arrangement including a channel disposed on the opposite side of the top rail 203 and the bottom rail, not shown. For example, the switch mechanisms SMIBIIA and SMIO0B respectively comprise supporting bases 22l and 222 projecting outwardly from the front of the supporting frame 200 and securing channels 23I and 232 disposed on the rear of the supporting frame 200; while the switch mechanisms SMIMIX and SMIO0Y respectively comprise supporting bases 223 and 224 projecting outwardly from the rear of the supporting frame 200 and securing channels 233 and 234 disposed on the front of the supporting frame 200. Of course, it will he understood that the portions of the supporting bases 22I, 222, 223, 224, etc., adjacent to the webs of the respective channels 23I, 232, 233, 234, etc., are retained mechanism SMIO0A will be described in detail.

As previously noted, the switch mechanism SMIO0A comprises a supporting base 22I, ten

vertically spaced-apart marking magnets MMIO I,

MMI02, MMI03, etc., and MMI00; a primary magnet PMI I I; ten primary bars PBI02, PBIIl3,

etc., and P3500; one hundred primary contact sets PCI II to PCI00, inclusive; and ten secondary contact sets SCIOI, SCI02, SCI03, etc., and

SC I 00. Also the switch mechanism SMI 00A comprises a marker switch I of the forward-stepping rotary type provided with an operating magnet MI23 which marker switch I20 is carried by the supporting base 22I adjacent to the lower end thereof and to the bottom rail, not shown.

Considering now the construction of the switch mechanism SMIO0A in greater detail, the primary magnet PMI II comprises a heel-piece secured to the supporting base 22I and carrying a core 302 supporting a winding 303. heel-piece 30I carries a pivot pin 304 supporting Also, the

and away from the core 302.. Associated with the armature 305 is a set of switch springs 306 comprising a plurality of individual resilient switch springs suitably insulated from each other by a plurality of interposed strips 301 and secured to the heel-piece 30I. The armature 305 carries an insulator 308 arranged in cooperative relation with respect to the switch springs 306. Also, the supporting base 22I is provided with an upper flange 303 and a lower flange, not shown, having aligned openings formed therein into which a primary operating element 3I0 is suitably journalled. A fixture 3 is rigidly secured to the upper end of the primary operating element 3I0 by a screw 3I2. The outer end of the fixture 3II is connected by a pivot pin 3I3 to alink 3I4; which is also connected by a pivot pin 3I5 to a tab 3I6 formed on the armature 305. The switch springs 306, due to their resiliency, act upon the insulator 308 to bias the armature 305 in the clockwise direction, as viewed in Fig. 4. away from. the end of the -core'302, whereby the primary operating element 3 I 0 is retained in its normal position illustrated in Fig. 4, by virtue of the connection including the link 3I4 between the armature 305 and the primary op' erating element 3 I 0.

In view of the foregoing description of the primary magnet PHI II, it will be understood that when the winding 303 is energized, the core 302 attracts the armature 305 causing it to be rotated in the counterclockwise direction, as viewed in Fig. 4, against the bias of the switch springs 306; whereby the primary operating element 3 I 0 is rotated in the counterclockwise direction, as viewed in Fig. 4, by virtue of the connection including the link 3I4, extending between the fixture 3H and the tab- 3I6. Subsequently, when the winding 303 is deenergized the switch springs 306 effect rotation of the armature 305 in the clockwise direction, as viewed in Fig. 4, back into its normal position by virtue of the action of the switch springs 306 upon the insulator 308 carried by the armature 305. When the armature 305 is thus returned to its normal position mentioned, the primary operating element 3I0 is rotated in the clockwise direction, as viewed in Fig. 4, back into its normal position by virtue of the connection including the link 3 I4.

As previously noted, the switch mechanism SMIO0A comprises ten marking magnets MMIOI to MMI 00, inclusive. The first marking magnet MMIOI is supported by a bracket 320 having a flat body portion 32I secured directly to the supporting base 22I by spaced-apart screws 322.

The body portion 32I of the bracket 320 termi nates in upper and lower flanges 323 and 324, respectively, arranged spaced-apart relation. and projecting outwardly from the body portion 32I to the right, as viewed in Figs. 2 and 5. Each of the flanges 323 and 324 is substantially Y-shaped; the upper flange 323 being provided with a front leg 325 and a rear leg 326; and the lower flange 324 being provided with a front leg 32! and a rear leg, not shown. The outer end of the front leg 325 of the upper flange 323 carries an upwardly directed stop 320; and the front leg 321 of the lower flange 324 carries an upwardly directed stop 329. The first primary bar PBI 0| is operatively associated with the first marking magnet MMIGI and is in the form of a strip of insulating material secured to the rear edge of a bracket 330 having a central opening 33I formed therein and provided with an armature 305 capable of movement toward spaced-apart front and rear upper tabs 332 and in substantially parallel,

. 33. an spaced-apart front and rear lower tabs 3-34 and 33,5, the bracket 330, the upper and an el ngated pivot pin 3 Projects; and th upper and lower rear tabs 333 and 335 are arranged in'alisnment with rc pect'to cachother and have aligned openings formed there-in, through which an elon ated pivot pin-337 pro- -jects; Similarly, in the bracket 32!], the upper and lower front'legs 325 and 321 respectively formed on the flan es 3,23 and 324 are arranged in alignment with respect to each other and have aligned openings formed therein, through which; an elongated pivot pin .338 projects; the upper and lower rear legs 32 6and, not shown, respectively formed on the flanges 323' and 324 are arranged in alignmentwith respect to'ejach otherand have aligned openings formed therein,

through which an elongated pivot pill .339 pro-.- lec'ts. The brack'et330 is pivotally mounted upon the bracket 320 by an arrangement comprising the four pivot pins 336, 331, 333 and 339 and four links, the upper two of which are shown at 340' and MI. More particularly, the upper rear link 34!) extends between the'upper ends of the pivot pins 331 and 339; the lower rear link), not shown, extends between the lower ends of the pivot pins 337 and 339; the upper front link 34! extends between the upper ends of the pivot pins 333 and 338; anda lower front link; not shown, extends between the lower ends of the pivot pins 333 and 338. Accordingly, the bracket 330 is mounted upon the bracket-320 for guided movement toward-and away from the bare-wire ban'k' 2H];

thereby to impart similar movements to the pri mary bar PBHH. p

The first marking magnet MMIOI comprises a heel-piece 342 secured to the flange 324 of the bracket 3'20 and carrying a core 343 supporting a winding 344. Also, an armature 345 provided with a downwardly extending arm34B is secured to the heel-piece 342 by an arrangement including a resilient spring 341'. Further, the first secondary contact set S| comprises two piles of switch springs 348 secured to the heel-piece "34,2

and cooperating with the arm 346 carried by the armature 345. More particularly; the arm 34-5 terminates in a. downwardly'extending projection 349 and forwardly and rearwardlyextendingprojections 35B cooperating, with the switch springs 343 'of the first secondary contact set SCIIH. Also, a fixture 35| is pivotally mounted upon the elongated pivot pin 33! and provided with upper and lower 'i'orward'ly ext-ending arms 352 and 353 respectively terminating in two operating lugs;

354 and 355. Also, the'fixture 35! carries a short forwardly projecting arm 353 disposed adjacent to the arm 353 and cooperating with" the downwardly extending projection 349 carried on the arm 343 of the armature 345. The fixture 35| isbiased in the clockwise direction,- as viewed in Fig. 5, by an arrangement including a coil spring 351 extending between the arm 353and the flange s24 carried bythe bracket 32o; Final ly, the primary operating elementilltl carriesa plurality of pairs of fixtures cooperating; with the arms of each fixture 351, etc. Specifically; the first pair of fixtures. carried by the primaryoperatingelement 3| ilcomprises the individual fix t-ures 353qand 359 respectively secured thereto by the screws 360' and 36.1 and cooperating with the rms 352: and 353 of the fixture35i| asso.oj i' atedfwith the bracket 330" supporting the first 1 adapted to en age the operating lug 453 carried n the outer end of the operating arm 352 urine fixture 35L 7 As previously noted, the switch mechanism Slvlmil'A comprises one hundred primary contact sets PCl H to PCIOQ, inclusive; the first ten pri-- mary Contact sets PC! to PC| it being associated with the first primary bar PBliil. Actually, the first ten. primary contact sets PCI l l to PC| Hi, inclusive, comprises the first ten conductor sets 2, etc., disposed adjacent to the top oithe bare-wire bank 2H) and ten springscts 4| etc, associated with the primary bar PBlol; the first spring set 4| cooperating with the first conductor set 2| i, as clearly indicated in Figs. 2 and 3. More particularly, each spring set 4| I, etc., comprises a positive line spring, a negative line spring and a control spring; thus, the primary'contact set PC'IH comprises the first conductor set 2!! in the'bare-wire bank 2||J and the first spring set 4H in the first group of ten spring sets. In the first group Of spring sets the individual springs are arranged in two sections including an outer spring and an inner spring disposed in staggered relation in order to prevent the individual springs from engaging each other; which springsets are mountedupon insulating strips 4 2 secured to the supporting base 22! and positioned between the body portion '32i of. the bracket 323 and the barewire bank 2H3 by an arrangement including a channel M3. The channel M3 retains the insulating strips 412 in clamped relation; whereby the inner ends of the individual springs in .the spring sets 4| I, etc., are retained in place; the outer ends of the individual springs in the spring sets 4| I, etc., are disposed adjacent to, but out of contactwith, the corresponding conductors in the conductor sets 2| I, etc. Finally, the inter mediate portions of the'individual springs in the spring sets 4| I etc, are retained in position by an arrangement comprising a plurality of teeth 4M and a plurality of intervening notches 415 formed in the first primary bar PBldi. As previously noted, the first primary bar PBloi is formed of insulating material; the notches M5 formed therein receive the individual springs in the outer section and the teeth 4M formed thereon engaged the individual springs in the inner section. Finally, the inner ends of the spring sets 4| I, etc comprise terminals which are wiredto' the ten riser busses RBHJ'I RE i 33, inclusive;

As best shown in. Fig. 5, an upstanding cable H6 is secured in place upon the channel 313 and disposed. etween the channel M3 and the pri elusive; and each. secondary contact set is cone nected' to a corresponding one of the riser bosses RBHH to R3103, inclusive. For example, this'is accomplished by connecting the ten spring/sets in the first group, including the'first spring set' 11 4H, respectively to the ten riser busses RBIUI to R3100, inclusive, in the cable 5 and by conmeeting the first riser bus RBIIIH in the cable M6 to the first secondary contact set SCH] l.

Considering now the mode of operation of the first marker magnet MMID it will beunderstood that when the winding 344 is energized the core 343 attracts the armature 345 causing it to rotate in the counterclockwise direction, as viewed in Fig. 2. When the armature 345 is thus operated, the arm 346 thereof, carrying the projections 349 and 350, is moved away from the heel-piece 342. The projections 35!] acting against the bias of the switch Springs 348 of the first secondary contact set SCIBI actuate the first secondary contact set SC I UI; and the projection 349, engaging the arm 356, rotates the fixture 35| in the counterclockwise direction, as viewed in Fig. 5, about the pivot pin .331. More particularly,the arms 352 and 353 of the fixture 35| are rotated from the full position to the dotted position, illustrated in Fig. 5; whereby the operating lugs 354 and 355 respectively carried by the arms 352 and 353 are moved into cooperative relation with respect to the operating lugs 353, etc., carried by the arms 352, etc., of the first pair of fixtures 358 and 359 supported upon the primary operating element 3 It. Specifically, the fixture 35l is rotated in the counterclockwise direction, as viewed in Fig. 5, against the bias of the coil spring 351; whereby the fixture 35 l, and consequently the bracket 330 carrying the first primary bar PBHH, are eifectively clutched to the primary operating element 3l0. At this time, in the event the primary magnet PMHI is operated, the primary operating element 3 0 is rotated in the counterclockwise direction, as viewed in Fig. 5, against the bias of the set of switch springs 306; all in the manner previously explained. When the primary operating element 3|0 is thus operated, the first pair of fixtures 358 and 359 cooperates with the first fix.- ture 351 and specifically, the operating lugs 363, etc., engage the operating lugs 354 and 355 respectively carried by the arms 352 and 353 on the fixture 35 l At this time only the first marking magnet MMIBI occupies its operated position; whereby only the first fixture 35l is operated. Accordingly, operation .of the primary operating element 3|0 is effective to operate only the first bracket 336 connected to the first primary bar PB l I! More particularly, the lugs 363, etc., carried by the first pair of fixtures 358 and 359, supported by the primary operating element 310, engage the lugs 354 and 355 respectively carried by the arms 352 and 353 on the first fixture 35!; whereby the first fixture 35l, and consequently the first bracket 330, are moved toward the rear, as viewed in Fig. 5, forcing the first primary bar PBHJI toward the'bare-wire bank 2H] against the bias of the first ten spring sets 4| etc. More particularly, the individual springs in the first ten spring sets are urged by the first primary bar PBHH into engagement with the first ten conductorsets 2| l, etc., in the bare-wire bank 2"]; whereby the first ten primary contact sets PC! I! to PC] I0, inclusive, are effectively actuated. Thus, at this time, the first ten primary contact sets PCI II to PCI Ill, inclusive, are actuated concurrently with actuation of the first secondary contact sets SCIOI. Hence, while the ten subscriber lines terminated by the first ten conductor sets 2| I, etc. are respectively connected to the ten riser busses RBIUI to RBI 00, inclusive, only the first riser bus'RB 0 l is connected to the test bus TBHIO.

Subsequently, when the winding 344 of the first marker magnet MMIDI is deenergized, the core 343 releases the armature 345; whereby the arm 346 is rotated in the clockwise direction, as viewed in Fig. 2, and returned to its normal position by virtue of the resiliency of the switch springs 348 of the first secondary contact set SC I 0 l; whereby the first secondary contact set SCHH is returned to its normal position. Also, the projection 349 carried by the arm 346 'disengages the arm 356 carried by the fixture -35| however, the fixture 35| is retained in its operated position while the primary operating element 3) .is. maintained operated. Subsequently, when the primary magnet PMI H is released, the primary operating element 3lll is rotated in the clockwise direction, as viewed in Fig. 5, back into its home position by the resiliency of the set of switch springs 305, as previously explained; whereby the operating lugs 363, etc., carried by the first pair of fixtures 353 and 359.disengage the operating lugs 354 and 355 respectively carried on the arms 352 and 353 of the fixture 351. At this time, the resiliency of the first ten spring sets 4| I, etc., forcethe first primary bar PBIOI- toward the front and away from the bare-wire bank 2|0; whereby the first ten spring sets 4, etc., are returned to their normal positions. Also, when the fixtures 358 and 359 disengage the fixture 35!, the coil spring 351 rotates the fixture 35| in the clockwise direction, as viewed in Fig. 5, back into its normal position. Finally, the first primary bar PBIBI urges the bracket 330 towards the front and away from the bare-wire bank 2H] back into its home position; whereby the front upper link 3M and the front lower link, not shown, respectively engage the stops 328 and 329 respectively carried by the arms 325 and 321 respectively carried by the flanges 323 and 324 of the bracket 320. At this time, the ten primary contact sets PCHI to PCHII, inclusive, as well as the first secondary contact set SCIOI, occupy their opencircuit positions.

In view of the foregoing description of the mode of operation of the first marking magnet MM [0| in conjunction with theprimary magnet PMI II to bring about the operation of the first ten primary contact sets PCI II to PCI [0, inclusive, and the first secondary contact setSClfll; it will be understood that the second marking magnet MMI02 is operative in conjunction with the primary magnet PMI II in a similar manner to bring about operation of the second ten primary contact sets PCI2| to PCI20, inclusive, and the second secondary contact sets SCIOZ, etc. In passing it is noted that the marker switch I20 of the switch mechanism SMIOIJA is operative step by step in order to select sequentially the marking magnets MMI 0 MMI 02, etc., in a manner more fully explained in conjunction with the electric circuit diagram.

In the operation of the switch mechanism SMIBIJA itwill be understood that the markin magnets MMIOI, MMIO2, etc., are operated and restored in sequence until the marking magnet finally operated corresponds to the desired group of subscriber lines, at which time the primary magnet PMlll'is energized in order to operate the primary operating element 3"), causing the primary bar corresponding to the desired group of subscriber lines to be operated in the manner described above; the primary bar mentioned being effectively clutchedto. the primary operating element-3H] at this time by virtue of the position of "the finally 'ope'iated' marking magnet'men:

into vibration its armature RAI I96. Finally, the link start relay RII80 completes, at the contacts H82, a path, includin the. contacts IIBI and the contacts II3I of the operated link relay RI I30, for applying ground potential to the first link start conductor CI IOI; whereby the start relay R630 in the finderj600is. operated. Operation of the start relay R630 in the finder 600 is effective to initiate operation'thereof in conjunction. with operation of the control circuit I009 in a manner more fully explained hereinafter in order to cause the switch mechanism SM600 to be operated promptly tofind the subs'cr'iber line 690 extending to the calling subscriber substation TGII in the ordinary case; whereupon the cut-through relay RIII in the allotter is operated. in order to prevent a timing operation therein.

However, assuniingfthat for some reason the finder 600 does not operate promptlyto find the subscriber line' 690 extending to the calling subscriber substation TSII, a timing operation is brought about in the allotter H09; whereby another idle link in the second group is assigned to find the subscriber line 990 extending to the calling subscriber substation TSII and the first link illustrated is released' More particularly, the vibrating armature RAI I 96 closes, at the contacts H98 and I199, a circuit, including the contacts H94, for operating the timer relay RI I90 shortly thereafter, the latter relay being of the slow-to-operate type. Upon operating, the timer relay RII90 prepares, at the contacts H94, an alternative circuit, including the contacts H91 and the contacts I I84, for energizing the winding 2 relay to restore; whereby the armature RAI I96 is again vibrated. The armature RAI I96 vibrates.

for a considerable time interval maintaining operated the timer relay RI I99 however, after a predetermined time interval the armature RAI I 96 settles down; whereby the contacts H97 and H98 are no longer completed alternately in order to effect restoration of the timer relay RI I90. Upon restoring the timer relay RI I90 interrupts, at the contacts I the previously mentioned circuit for maintaining operated the control relay RI I85;

however, the latter relay does not restore immediately since it is of the slow-to-release type. Also, upon restoring the timer relay RI I90 completes, at the contacts H93, a circuit, including the contacts H84, IIBl, H54, H33. H14, H34 and i I55, for energizing the upper winding of the link relay RI i'iein series with the upper winding of the link disconnect relay RI I60, thereby to cause the latter relays to operate. Upon operating the link disconnect relay RIIBU interrupts, at the' contacts IIi'iI, the previously traced path for applying ground potential to the first link start conductor CII9I extending to the first link illus trated in order to effect restoration of the startrelay R830 in the finder 900 and the consequent release of the first link. Further, the link disconnect relay RI I69 completes, at the contacts I I63, a holding circuit, including the contacts II I9, I llil, I I93 and I [84, for energizing the lower winding thereof. Upon 'operating the link relay 16 RI I20 interrupts, at the contacts H26, the previously traced series holding circuit for energizing the lower winding of the link relay RI I30 and the lower winding of the fault relay RI Mil and the winding of the reset relay RI I45, thereby to cause the link relay RI I30 to restore immediately; the reset relay RI I45 does not restore immediately, since it is of the slow-to-release type. Also, the link relay RI I29, upon operating, completes, at the contacts H25, a holding circuit, including the contacts HIS, II'42'and H52, for energizing the lower winding thereof in series with the lower winding of the fault relay RI I40 and the winding of the reset relay RI I; whereby the link relay RI I29 and the reset relay RI I45 are maintained in their operated positions. Further, the link relay RI I23 prepares, at the contacts II2I, a path for applying ground potential to the link start conductor CI I33 extending to the finder of the associated intermediate link. When the control relay RI H35 restores, it interrupts, at the contacts IIB'I, the previously traced holding circuit for energizing the lower winding of the link disconnect relay RI I60, thereby to cause the latter relay to restore at this time, since the previously traced circuit for energizing the upper winding of the link, disconnect relay RI I in series with the upper winding of the link relay RI I29 was interrupted, at the contacts I I34, of the link relay RI I39 incident to restoration thereof. Upon re storing the link disconnect relay RI I60 completes,

at the contacts I I6 I, a path including the contacts H82 and II2I of the operated link relay RIIZil for applying ground potential to the link start conductor CI I93 extending to the finder of the intermediate link; finder of the intermediate link proceeds. specifically, the finder of the intermediate link mentioned cooperates with the control circuit I969 to hunt for the subscriber line 690 extending to the calling subscriber substation TBII in a manner identical to that of the finder 600 of the first link illustrated described below.

Now assuming, that the finder 690 of the first link operates promptly to find the subscriber line 09!! extending to the calling subscriber substation Tell and before operation of the timing apparatus in the allotter H00 in the manner described above; upon operating the start relay R6323 in the finder B00 completes, at the contacts 038, path for applying ground potential to the hunt' conductor Ci I68; whereby a circuit, including the contacts II9I and I023, is completed for operating the start relay RIQIG in the control circuit I000, when the timer relay RI I in the allotter" I I00 closes the contacts I I9I. Upon operating the start relay RIOI0 completes, at the contacts IOI I, Y a path, includingthe contacts I02I and I03I, for applying ground potential tothe pulse conductor C I 009, thereby to complete a circuit, including the contacts 635 of the operated start relay R630 in the finder 600, for energizing the magnet M623 T When the magnet of the marker switch 620. M623 is thus energized, it operates immediately to whereby operation of the More energizing the upper winding of the step relay RI030 in the control circuit I000, thereby to cause the latter relay to operate. Upon operating the step relay RI030 completes, at the contacts I034, a holding circuit, including the contacts I048, I053 and IOI3, for energizing the lower winding thereof. Also, upon operating, the start relay R630 in the finder 600 completes, at the contacts 631, a circuit for energizing the lefthand winding of the test relay R640, thereby to render the latter relay exceedingly fast to operate when the right-hand winding thereof is subsequently energized. When the wiper 62I of the marker switch 620 engages the first contact in the associated contact bank, a circuit, including the contacts 636 of the operated start relay R630, is completed for energizing the first marking magnet MM60I thereby to cause the first marking magnet MM60I to operate and to clutch the first primary bar PB60I to the primary operating element associated with the primary magnet PM6I I and to operate the first secondary contact set SC60I. When the first secondary contact set SC60I is thus operated, the test bus T3600 is connected to the first riser bus RB60I for a purpose more fully explained hereinafter.

.Also, when the step relay RI030 in the control circuit I000 operates, it interrupts, at the contacts I03I the previously mentioned path for applying ground potential to the pulse conductor CI005, thereby to interrupt a multiple circuit for energizing the magnet M623 of the marker switch 620 in the finder 600 and the upper winding of the step relay RI030; whereby the magnet M623 restores and the step relay RI030 is maintained in its opera-ted position due to the completed holding circuit for energizing the lower winding thereof. When the wiper noted of the marker switch 620 is driven from its home position, the set of switch springs S626 is actuated for a purpose more fully explained hereinafter. Also, when the step relay RI030 in the control circuit I000 operated, it completed, at the contacts I032, a path, including the contacts IOI3, I043 and I MI and the associated resistor, for energizing the upper winding of the transfer'relay RI050, thereby to cause the latter relay to operate since the lower winding of the transfer relay RI 050 was energized incident to operation of the start relay RIOI0. The transfer relay RI050 is of the polarized type and after the lower winding thereof was energized via the circuit completed, at the contacts N3 of the operated start relay RIOI0, it operates exceedingly fast when the upper winding thereof is subsequently energized via the circuit completed, at the contacts I032 of the operated step relay RI 030. Upon operating the transfer relay RI050 interrupts, at the contacts I053, the previously traced holding circuit for energizing the lower winding of the step relay RI030, thereby to cause the latter relay to restore, since the previously traced circuit for energizing the upper winding thereof was interrupted, at the contacts 625, incident to restoration of the magnet M623 of the marker switch 620 in the finder 600.

Also incident to operation of the start relay RIO| there is completed, at the contacts IOI3, a circuit, including the contacts I046 and I06I, for operating the first counting relay RI065. Upon operating the first counting relay RI065 completes, at the contacts I330, a circuit, including the contacts IOI3 and the contacts I000 and I093, arranged in multiple, for operating the reset-relay RI060. Also, the first counting relay RI 065 completes, at the contacts I068, an alternativeholding circuit including the contacts I012, I011, I082, I08! and IOI3 for energizing the winding thereof. Upon operating the reset relay RI060 interrupts, at the contacts I06I, the previously traced original circuit for energizing the Winding of the first counting relay RIMS; and completes, at the contacts I062, a holding circuit, including the multiple contacts I089 and I093, as well as the contacts IOI3, for energizing the winding thereof.

Further, the first counting relay RI065 completes, at the contacts I066, a connection including the contacts I095 between the lower winding of the stop relay RI020 and the first group start conductor CI002; whereby the stop relay RI020 tests to determine whether the calling subscriber line is included in the first group of ten subscriber lines accessible to the finder 600. In the present example, the subscriber line 690 extending to the calling subscriber substation T6 is included in the first group of ten subscriber lines accessible to the finder 600; whereby ground potential appearing upon the first group start conductor CI002 completes a circuit for energizing the lower winding of the stop relay RI020 in order to cause the latter relay to operate. Upon operating the stop relay RI020 interrupts, at the contacts I023, the previously traced circuit for maintaining operated the start relay RIIIIB, thereby to cause the latter relay to restore shortly thereafter, it being of the slow-to-release type. Also, the stop relay RI020 completes, at the contacts I024, a holding circuit, including the contacts Hill and the grounded hunt conductor CII08, for energizing the upper winding thereof. Further, the stop relay RI020 interrupts, at the contacts I02I, a further point in the previously traced path for applying ground potential to the pulse conductor C I 005, thereby positively to prevent further operation of the magnet M623 of the marker switch 620. Finally, the stop relay RI020 prepares, at the contacts I022, a path, including the contacts I03 I, for applying ground potential to the primary magnet conductor CI003; which path is completed, at the contacts IOI2, incident to the restoration of the start relay RIOI0. The application of ground potential to the magnet conductor (H003 completes a circuit, including the contacts 63I, for operating the primary magnet PMGI I in the finder 600. Also, upon restoring, the start relay RIO I0 interrupts, at the contacts IOI3, the previously traced multiple circuits for energizing the upper and lower windings of the transfer relay RI050, thereby to cause the latter relay to restore; and interrupts, at the contacts IOI3, the previously traced multiple holding circuits for maintaining operated the reset relay RI060 and the first counting relay RI065 in order to cause the latter relays to restore.

When the primary magnet PM6II of the switch mechanism SM600 in the finder 600 is operated, the first primary bar PB60I clutched to the primary operating element by the operated first marking magnet MM60I is operated; whereby the first group of ten primary contact sets PCBII, PC6I2, etc., and PCB") are operated to connect the subscriber lines in the first group of ten to the ten riser busses RB60I, R3602, etc., and RB600, respectively. Also, at this time the first secondary contact set SC60I is operated by the operated first marking magnet MM60I, thereby to connect the first riser bus RB60I directly to the test bus TB600. Accordingly, in the event the calling subscriber line is connected to the firstriser bus J-RBSE i, a .circuit is -;immediately rompleted for energizing the right-hand winding of the test relay REM]; which, ofrcourse, is the present case,=since the subseriberline-fififi is.con-nected via the first primary contact set PCfiil-l in the first group of ten to the first riser bus R360]. When the'right-hand winding of the testrelay R64!) is thus energized, it operates exceedingly fast to interrupt, atthe contacts t.|, apoint in a'ci-rcuit-that wouldhavebeen completedior effecting reoperation of the magnet M623 of the marker switch 6.28. .More particularly, when the primary magnet PMGH :operated to operate the ten primary contactsets :PCB H ,=etc., it ultimately prepared, at the contacts 612, :at the end of its operating stroke, a circuit including the contacts 54 i, 63.3 and 824, for operating the magnet M623 of the marker switch 5.21%; which circuit would have been completed had'it not been for the operation of the test :relay R640 exceedingly .fast, in the present example, to interrupt, at the contacts @BM the circuit above-traced. Accordingly, in the presentexample-sincethe calling subscriber line 69!} is-terminatedin thefirst primarycontact set PO65 l in the first group often, it is not necessary .to .reoperate the marker switch 620 beyond-the position wherein the -wiper fi2l thereof engages the first contactinthexassociated contact'bank.

Further, the test relay Riificompletes, at :the contacts 642, an obvious path for short-circuit ing the right-hand winding thereof; whereby direct ground potential, at the contacts 638, is applied via the control conductor of the test bus TBfiEiiJ to the control :conductor of .the first riser bus R350 L and consequently to the control conductor G694 of the subscriber line 699 having battery potential thereon markingthe subscriber line 690 .as thecallingsubscriber line, as previously explained. The application of direct ground potential to the control 1conductor'C894 of the subscriber line 699co1npletes a circuit including the contacts 658 for-operating the cut-off relay R6556 in the line circuit 650 individual to the subscriber line 695. Upon operating, the cut-off relay R660 interrupts, at the contacts 663, the previously mentioned path for applying battery potential by way of the resistor 4655 to .the control conductor (3-594 of r-the subscriber line 690; and completes, .at the contacts-664., a holding circuit for energizing the winding thereof from "the grounded control conductor C594 of-the subscriber line 650. Further, the cut-01f relay R660 interrupts, at the contacts 664 and 682,

the previously traced loop [circuit extending between the calling subscriber substation T6 and the left-hand and right-hand 'windings of the line relay R655, thereby to cause the .latter relay to restore. Upon restoring the line relay R855 completes, at the contacts .65-'l,.a -path, including the contacts 1664, between the control conductors C693 and 05.94 .of the subscriber line 1590, thereby to continue [the marking of the subscriber line 690 as busy to the connectorstfib, etc., in the secondgroup having-access thereto. Further, upon restoring the :line relay R655 interrupts, at thecontacts 659, the previously mentioned path for applying .ground potential to the first group start conductorCl-DUZ, thereby to interrupt the previously traced circuit for maintaining operated the start relay RI I in the ,allotter H00 and for'energizing the lower winding of the stop relay R5926 :in thelcontrol :circuit I000. Further, the test-relay R640 in :the finder fillfl completes, tat theicontactsdifl, apathincluding the contacts 639 for applying ground potential-to the cut-through conductor "0116], thereby to "complete obvious multiple circuits *for energizing the winding of the cut-through relay RI I'll! and the-.upper-wmding of-the link start relayiEtl I81] in the allotter Hall; whereby the cut-through relay RH'JH) operates and the link start relayzRtl-flfi is maintained operated, notwithstanding the restoration of thestart relay RH15 as previously noted. Further, the test relay R640 completes, at the contacts 648, an obvious holding circuit for maintaining operated the primary vmagnet PMS subsequent to itherel'ease of the startzelay R535; and completes, at the contacts 641,,an obvious ,holding circuit for maintaining operated the first marking 'magnet MMBU I subsequent to ,the release of the start .relay R630 and {completes, at thecontacts adian obviouscircuit for operating ;the connect relay-.,R625. Upon operating the connect re R92 5 completes, at its :associated contacts, an 'obvious-zconnection between the test .bus TIBfiflG and-the trunk'130;-in.order to complete a loop circuit extending from the calling subscriber substation 'TBH to the upper and lower windings of the line :relay R15!) in the selector iilil; whereby the line :relay R750 operates. further, "the .test relay R866 in the finder 590 completes, at the contactsfifi, a path, including the :contacts 263?, for applying ground potential to the control-conductor C133 of the trunk 136, thereby tocempletea circuitfor-energizing the lower winding-of the'test relay R140 in the selector 1706 in order to render the latter relay exceedingly fast tooperatewhen the :upper windingthereof is subsequently energized, since the testirel'ay t-R-ifl is of the polarized type. Finally, the 'testirelayRfiit-iliinithe finder 60D interrupts, at the contacts 666, one of the multiple paths :for applying ground-potential .to the linksbusy conductonC-M 09 extendingto the linksbusy relay Ri-iiizil the allotter -H:fl0 for the "purpose previously explained.

Upon operating the linerelay R-l250ih the-selector Hm completes, atthe contacts 'I52, an obvious circuitior operating the hold relay RT-B0. Upon operating the hold relay R160 completes, at the contacts J65,a path'iorlapplying ground potential by way \Qf the upper winding of the test relay R340 to the iCOIltI'O]. conductor :of the test bus T13 .and completeaat.theicontacts 166, a multiple ,path for applying ground potential to the control conductorca'laiiof the trunk *1 30, thereby to maintain operated the test :relay R649 in the finder 60,0subsequent to restoration of the start relay R630 therein. Finally, the .;hold relay R160 completes, :atthe contacts E61, apath for applying ground potential to the first'guard conductor Clv 12 extending into the shutter l 1013, thereby to complete; a circuit, including the contacts .I I34 and l l55,f.or energizingun series the upper windingof the link relayRttZli and the .upper winding of the .link disconnect relay Ruse; whereby the relays mentioned operate. Upon operating thelinkrelayRl-l 20 eftects restoration of the-link relay RI H30 in :the manner previously explained; whereby ground potential is removed at the contacts M3! from the first link start conductor Ohio-l extending i the :finder ten in order to cause the start .relay R630 therein to :restore. Uponrestoring the start relay R630 interrupts, at the contacts 16;, 634, 635,639 and 630, the connections between the finder 60,8 andthe controlcircuit [000 and the allotter H00. At this time, the primary magnet PMs I .l, the firstimarking ,magnet .MMSDI and the connect :relay R625 are retained in their operated positions by 'virtue of the completed holding circuits therefor maintained by the operated test relay R640. Accordingly, at this time, the finder 600 has operated to find the subscriber line 690 extending to the calling subscriber substation TBI I and to connect the subscriber line 690 to the trunk 130 extending to the selector 100; whereupon the selector 100 is conditioned to be responsive to the first digit dialed at the calling subscriber substation 090 to the trunk 130 extending to the selector 100; whereupon the selector 100 is conditioned to be responsive to the first digit dialed at the calling subscriber substation TBII in a manner more fully explained hereinafter.

' Upon operating the cut-through relay RI I10 in the allotter H interrupts, at the contacts I I1I the holding circuit for energizing the lower winding of the link start relay RII80, thereby to cause the latter relay to restore, since the start relay R630 in the finder 000 has, by this time, restored to interrupt, at the contacts 030, the previously traced multiple circuit for energizing the winding of the cut-through relay RI I10 and the upper winding of the link start relay RI I80. Also, upon operating the cut-through relay RI I10 completes, at the contacts H12, an obvious path for short-cirouiting the lower winding of the fault relay RI I 00, thereby positively to prevent the operation of the latter relay incident to operation of the link relay RII20 and prior to restoration of the link relay RI I30. Finally, the cut-through relay RI I10 completes, at the contacts I I13, a holding circuit including the contacts I I63 for energizing the lower winding of the link disconnect relay RI I00. Shortly thereafter the cut-through relay RI I10 restores since it is of the slow-to-release type, interrupting, at the contacts I I12, the previously mentioned path for short-circuiting the lower winding of the fault relay RI I40; and interrupting, at the contacts H13, the holding circuit for energizing the lower winding of the link disconnect relay RI I60; whereby the latter relay restores, since it is assumed that, by this time, the link relay RI I20 has completely operated eifecting the restoration of the link relay RI I30. Upon restoring the link start relay RI I 80 interrupts, at the contacts I I 82, a further point in a path, including the contacts II6I and II2I, for applying ground potential to the link start conductor CI I03 extending to the intermediate link. Also, the link start relay RI I 80 interrupts, at the contacts H84, the circuits for maintaining operated the timer relay RI I00 and the control relay RI I85, thereby to cause the latter relays to restore, the control relay RI I05 being slow to release as previously noted. At this time the control circuit I000 and the allotter H00 are completely released and available for further use.

Now assuming that the call is initiated at the subscriber substation T602, included in the second 100 group, the line relay R615 in the line circuit 610, individual to the subscriber line 695, extending to the calling subscriber substation T602 operates; thereby to initiate operation of the control circuit I000, the allotter I I00 and the finder 600 in a manner substantially identical to that previously described. However, in this'case, since the calling subscriber line 605 terminates in the primary contact set PC2602 in the switch mechanism SM600, considerable operation of the control circuit I000 in conjunction with the switch mechanism SM000 proceeds before the calling subscriber line 53. i ound, as the pri- 22 mary contact set PC602 is arranged in the tenth group of ten primary contact sets in the switch mechanism SM600.

More particularly, the first time the step relay RI030 in the control circuit I000 operates, operation of the transfer relay RI050 is brought about as previously explained, while the first counting relay RI005 occupies its operated position. At this time, the previously traced circuit for energizing the lower winding of the stop relay RI 020 is not completed, since the winding mentioned is connected at the contacts I066 to the first group start conductor CI002; whereas ground potential appears upon the tenth group start conductor CIO0I, since the calling subscriber line 095 appears in the tenth group of subscriber lines accessible to the switch mechanism SM600 as previously noted. Accordingly, when the magnet M623 of the marker switch 020 restores it interrupts, at the contacts 025, the previously traced path for connecting the pulse conductor CI005 to the interrupter conductor OM00, thereby to interrupt the previously traced circuit for energizing the upper winding of the step relay RI030; assuming that the transfer relay RI050 has operated to interrupt, at the contacts I053, the previously traced holding circuit for energizing the lower winding of the step relay RI030. Upon restoring the step relay RI030 recompletes, at the contacts I03I, the previously traced path for applying ground potential to the pulse conductor CI005, thereby to bring about reoperation of the magnet M023 of the marker switch 620 in order to drive the wiper noted thereof an additional step in the clockwise direction. Also, upon operating the magnet M023 recompletes, at the contacts 025, the previously traced connection between the grounded pulse conductor CI005 and. the interrupter conductor C1004; whereby the previously traced circuit for energizing the upper winding of the step relay RI030 is recompleted, causing the latter relay to reoperate.

The magnet M623 of the marker switch 020 in the finder E00 cooperates with the step relay RI030 in the control circuit I000 in the manner described. above; whereby the step relay RI030 operates and restores repeatedly; and the magnet M623 operates and restores repeatedly, thereby to drive the wiper noted of the marker switch 620 step by step in the clockwise direction. When the wiper 02I of the marker switch 020 disengages' the first contact and engages the second contact in the associated contact bank, the previously traced circuit for first marking magnet MMO0I is interrupted and a substantially identical circuit is completed forcperating the second marking magnet MM002; whereby the first marking magnet MMO0I restores and the second marking magnet MM002 operates. Accordingly, as the marker switch 020 is driven step by step, the marking magnets MM60I, MM002, etc., are operated and subsequently restore in sequence; whereby the corresponding primary bars PBO0I, P5002, etc., are effectively clutched and then declutched from the primary operating element; and the corresponding secondary contact sets SCO0I, S0002, etc., are operated and then restored. As the secondary contact sets SCO0I, S0002, etc., are operated and then restored, the riser busses RBO0I, R3002, eta, are connected and then disconnected from the test bus T3000.

Considering now the operation of the control circuit I000 in greater detail, the first time thewhereupon the latter relay restores,

maintaining operated the- 

